This invention relates to a method of reading a bar code which indicates an information on an article.
Bar code systems are used effectively in the situation that the products, which are mass-produced, especially produced in various types, distributed and transported, are assorted according to their objectives in the highly reliable, quick, automatic and energy saving condition.
The above-described bar code systems are classified into optical or other non-contact types and electrical or other contact types. The former types are used more often than the other types except in certain cases and the optical reflection system using a light beam is the actual type of the most cases.
FIG. 3 shows an example of a method for reading a bar code printed on the surface of a cylindrical object, a cartridge of photo film, during its transportation.
On cartridge 1, DX code 2, indicating characteristics and other information about the film, is printed on the cylindrical surface as shown in FIG. 4, and bar code 3, relating to manufacture and additional informations, is printed on one or both sides of the surface.
Cartridge 1 is set at a position on carrying belt 4 where light beam 6 from bar code reader 5 irradiates exactly bar code 3 by the precise positioning unit. When the cartridge comes to the reading position on carrying belt 4, it is detected by a pair of photoelectric sensors 7, the light beam 6 scans the bar code 3 in a vertical direction and reads the bar code. However, since cartridge 1 is being transferred, the bar code must be read at high speed and in a snort time.
As described above, the cartridge must be precisely positioned on the carrying belt beforehand and, since the reading time is limited, malfunction is likely to occur. In order to prevent malfunctions, the carrying speed should be slower or the bar code should be larger in size; these are disadvantages to result in a decrease in efficiency.